Transient and ectopic expression of lumican by acinar cells in L-arginine-induced acute pancreatitis

Lumican as a novel marker for differential diagnosis of Bowen disease and actinic keratosis

Lumican, a member of the small leucine-rich proteoglycan family, regulates the assembly and diameter of collagen fibers in the extracellular matrix of various tissues. Lumican expression correlates with pathological conditions, including skin fragility, corneal opacification, and corneal and cardiac wound healing. Lumican is overexpressed in tumor cells, including in the breast, colorectal, neuroendocrine cell, uterine cervical, and pancreatic cancers. Lumican expression also correlates with the growth and metastasis of various malignancies. For example, lumican expression is lower in the dermis of malignant melanoma cases than in early-stage melanomas. However, the expression patterns and roles of lumican in nonmelanoma skin cancer have not been elucidated. In this study, we used immunohistochemistry and in situ hybridization to examine the expression patterns of lumican in normal skin, Bowen disease, and actinic keratosis. In normal skin, lumican was expressed in the collagen fibers in the dermis, acrosyringium, follicular epithelium, and sebocytes but not in epidermal keratinocytes. In Bowen disease, lumican was expressed in 34 (91.8%) of 37 patients. Notably, all cases of actinic keratosis were negative for lumican. These findings suggest that lumican plays an important role in the pathogenesis of Bowen disease and actinic keratosis and might be useful as an adjunct to the diagnosis for subtypes of 2 diseases: bowenoid actinic keratosis and Bowen disease in sun-exposed areas.

Oxymatrine ameliorates L-arginine-induced acute pancreatitis in rats

The aim of this study was to determine whether oxymatrine has a protective effect against acute pancreatitis (AP) in a rat model of L-arginine-induced AP. AP was induced by two intraperitoneal injections of L-arginine (250 mg/100 g) at a 1-h interval. Oxymatrine (50 mg/kg) was administered every 6 h after the induction of AP. Oxymatrine significantly reduced the plasma amylase, D-lactic acid and tumor necrosis factor alpha concentration, serum diamine oxidase and lipase activity, and pancreatic myeloperoxidase activity, which were increased in AP rats (P < 0.05). In addition, the pancreatic CD45 expression and the expression of claudin-1, but not zonula occludens-1 (ZO-1) and occludin, in the intestinal tissues were significantly reduced after the induction of AP. However, oxymatrine increased the expression of claudin-1 and CD45, but did not alter the expression of ZO-1 and occludin. In conclusion, our results demonstrated that oxymatrine is potentially capably of protecting against L-arginine-induced AP and attenuating AP-associated intestinal barrier injury by up-regulation of claudin-1.

L-Arginine-induced acute pancreatitis results in mild lung inflammation without altered respiratory mechanics

Acute lung injury is a common complication of acute pancreatitis (AP) and contributes to the majority of AP-associated deaths. Although some aspects of AP-induced lung inflammation have been demonstrated, investigation of resultant changes in lung function is limited. The aim of this study was to characterize acute lung injury in L-arginine-induced AP. Seven groups of male Sprague-Dawley rats (n = 4-10/group) received 2 intraperitoneal (i.p.) injections of L-arginine (250 mg/100 g) at 6, 12, 24, 36, 48, or 72 hours before measurement of lung impedance mechanics. Control rats (n = 10) received i.p. saline. Bronchoalveolar lavage (BAL), plasma, and pancreatic and lung tissue were collected to determine pancreatic and lung measures of acute inflammation. AP developed between 6 and 36 hours, as indicated by increased pancreatic abnormal acinar cells, myeloperoxidase (MPO) activity, edema, and plasma amylase activity, before beginning to resolve by 72 hours. In the lung, MPO activity increased (2.4-fold) from 12 hours, followed by a modest increase in lung edema at 48 hours, with increased BAL cell count (2.5-fold) up to 72 hours (P < .05). In contrast, no significant changes in lung mechanics were evident over the same period. Despite measurable lung inflammation, no significant deterioration in respiratory function resulted from L-arginine-induced AP.

Utility and control of proteoglycans in tissue engineering

This review addresses various methods of integrating proteoglycans (PGs) into the design of engineered tissues and provides insight for designing tissue-engineered disease models that leverage current knowledge of PG biology. Even though PGs show immense possibilities in tissue-engineering applications, they have seldom been used to their full potential. The most common tissue-engineering application of PGs has been in scaffolds (matrigels and collagen-chondroitin sulfate matrices), in which PGs or their glycosaminoglycan (GAG) chains are incorporated into the scaffold to promote cell growth, tissue remodeling, and intracellular signaling. In addition, many studies have reported the total amount of PGs synthesized within engineered tissues but have not delineated which specific PGs or GAG classes are involved in engineered tissue development. In native tissues, various PGs are dynamically and differentially regulated to achieve specific biophysical and biological functions, such as compressibility and transparency. Therefore, the targeted modulation of specific PGs (via exogenous addition, endogenous stimulation with growth factors, or mechanical stimulation) may help engineered tissues to achieve native tissue properties. The PG composition of engineered tissues could also be modified to achieve disease models in vitro and thus provide a way to study the effect of external agents on PG-related disease mechanisms.

Role of the small leucine-rich proteoglycan (SLRP) family in pathological lesions and cancer cell growth

The roles of lumican, a member of the small-leucine-rich-proteoglycan (SLRP) family, in pathological fibrosis, cancer tissues and tumor cell growth were reviewed. Lumican is predominantly localized in the areas of pathological fibrosis including the thickened intima of human coronary arteries, ischemic and reperfused hearts, and acute pancreatitis and chronic pancreatitis (CP)-like lesions adjacent to pancreatic cancer nests. In these lesions, lumican mRNA and protein were transiently and ectopically overexpressed in most of the vascular smooth muscle cells (VSMCs) that migrated into the thickened intima, myocardial cells adjacent to an ischemic lesion, acinar cells, islet cells and fibroblasts of pathological pancreatic tissues. The low expression level of lumican in breast cancer is associated with rapid progression and poor survival. Lumican mRNA in breast cancer is overexpressed in fibroblasts adjacent to cancer cells but not in cancer cells. Furthermore, the high expression level of lumican is associated with a high pathological tumor grade, a low estrogen receptor level in the cancer tissues, and young age of patients. The suppression of lumican expression in culture cells induces their cell growth. Lumican-transfected tumor cells are characterized by a strong suppression of their anchorage-independent growth and capacity of invasion. Lumican significantly suppressed subcutaneous tumor formation in syngenic mice, with a concomitant decrease in cyclin D1 expression level, and induced and/or enhanced the apoptosis of these cells. The autocrine mechanism in cancer cells and the paracrine mechanism in cancer cells and fibroblasts via transforming growth factor (TGF)-beta and Smad signals may play important roles in the regulation of tumor growth by SLRPs.

Pancreatite aguda experimental induzida pela L-arginina: avaliação histológica e bioquímica

RACIONAL: Doses excessivas de aminoácidos básicos como a L-arginina têm a capacidade de lesar o pâncreas de ratos. OBJETIVO: Descrever e avaliar as características bioquímicas e histológicas da pancreatite aguda induzida pela L-arginina em ratos durante a instalação, desenvolvimento e reparação do processo inflamatório pancreático. MATERIAL E MÉTODOS: A amostra constituiu-se de 105 ratos machos, da linhagem Wistar. Aos ratos do grupo experimento (n = 70) administrou-se injeção intraperitonial de 500 mg/100 g de peso corporal de L-arginina. No grupo controle (n = 35) foi injetada solução salina isotônica. Analisaram-se 10 animais do grupo experimento e 5 do grupo controle em cada período de 6 h, 12 h, 24 h, 48 h, 72 h, 7 dias e 14 dias. Durante os tempos determinados coletou-se sangue para exames laboratoriais e o pâncreas para análise em microscopia óptica. RESULTADOS: Doze a 24 horas após a injeção de L-arginina os níveis séricos de amilase atingiram valores máximos, comparados àqueles dos ratos controle, decrescendo gradualmente, alcançou-os na 48ªhora sendo significativamente menor após 72 horas e 7 dias. A atividade enzimática retornou a níveis basais após 14 dias. Os valores de amilase estavam normais em todos os tempos avaliados nos animais do grupo controle. Na microscopia óptica, após injeção de L-arginina, observou-se arquitetura pancreática histologicamente preservada no período de 6 horas, evidenciando-se em 24 horas importante edema intersticial. Após 48 horas, a arquitetura acinar estava parcialmente destruída com necrose celular focal, atingindo sua máxima severidade ao ultrapassar 72 horas. No 7º dia a necrose tecidual e o edema haviam diminuído, iniciando-se a regeneração da arquitetura acinar. Observou-se a reconstrução estrutural pancreática após 14 dias. No grupo controle não se encontraram alterações histológicas pancreáticas. CONCLUSÃO: A pancreatite aguda experimental induzida pela L-arginina induz a necrose pancreática, apresentando evolução auto-limitada com regeneração do pâncreas em 2 semanas.

L-arginine-induced experimental pancreatitis

Despite medical treatment, the lethality of severe acute pancreatitis is still high (20%-30%). Therefore, it is very important to find good animal models to characterise the events of this severe disease. In 1984, Mizunuma et al^[1] developed a new type of experimental necrotizing pancreatitis by intraperitoneal administration of a high dose of L-arginine in rats. This non-invasive model is highly reproducible and produces selective, dose-dependent acinar cell necrosis. Not only is this a good model to study the pathomechanisms of acute necrotizing pancreatitis, but it is also excellent to observe and influence the time course changes of the disease. By writing this review we iluminate some new aspects of cell physiology and pathology of acute necrotizing pancreatitis. Unfortunately, the reviews about acute experimental pancreatitis usually did not discuss this model. Therefore, the aim of this manuscript was to summarise the observations and address some challenges for the future in L-arginine-induced pancreatitis.